TRANSMISSION OF VENEZUELAN EQUINE ENCEPHALOMYELITIS VIRUS BY STRAINS OF AEDES-ALBOPICTUS (DIPTERA, CULICIDAE) COLLECTED IN NORTH-AMERICA AND SOUTH-AMERICA

Experimental studies were undertaken to ascertain the vector potential of North American (Houston and Alsace) and South American (Sao Paulo and Santa Teresa) strains of Aedes albopictus (Skuse) for an epizootic (Trinidad donkey) strain of Venezuelan equine encephalomyelitis (VEE) virus. Infection rates were similar in all four strains of Ae. albopictus tested after ingestion of VEE virus from a viremic hamster. Virus disseminated from the midgut to the hemocoel in about 80% of infected mosquitoes, regardless of the dose ingested (10(4.6) to 10(5.7) plaque-forming units per mosquito) or the time of extrinsic incubation (7-35 d). Although all four strains of this mosquito transmitted VEE virus by bite to hamsters, transmission rates were significantly higher for the South American strains (24%, 40 of 170) than for the North American strains (5%, 9 of 165). Although VEE virus has never been isolated from Ae. albopictus, the introduction of this species into the Americas may allow it to serve as an amplification vector in areas where epizootic strains of VEE are found or introduced.